This invention relates generally to drum structure, and more particularly to tensioner holding, preventing or blocking loosening of adjusted tensioner structure.
In the past, drum tensioner rods have been employed and adjusted to produce selected tensioning of drum heads. Such adjusting is typically effected by tightening rotating tensioner rods to produce desired drum head stretching, or tension. Such rotation adjusts the screw thread connection of the rods with lugs located at the outer side of the drum shell.
It is found that such tensioner rods can become loosened over time, due to repeated shock loading of the drum head, drum shell transmitted to the tensioner rods. Such impact loading facilitates unwanted rotation of the rods in loosening directions, and some rods can loosen more than others. There is need for a way to prevent or block such relative loosening of the rods, without preventing rotation adjustment of the rods to achieve desired stretching of the drum head for production of desired drum sounds, when struck.
It is a major object of the invention to provide tensioner rod holding, or holding structure, meeting the above need. In this regard, a drum typically includes a flange defining a through opening for passing the tensioner rod, the flange acting to tension the drum head. In this environment, the invention basically comprises:
a) a seating surface on the flange in close association with that opening, and
b) a grommet to receive loading transmitted by the tensioner rod and having a shoulder or shoulders engaging the seating surface in such a way as to transmit loading to the flange, the grommet blocking loosening rotation of the tensioner rod, relative to the flange.
It is another object of the invention to provide a grommet as referred to, and wherein the shoulder or shoulders is or are tapered to receive a tensioner rod load transmitting shoulder. Multiple such wedging shoulders may be spaced about an axis defined by the grommet, and angled to resist loosening, rotation of serrations defined by the flange, but without preventing tensioner rod adjustment. Such individual multiple shoulders enhance the frictional effect that contributes to blocking of undesired loosening rotation of the tensioners.
An additional object is provision of multiple splits, in the grommet, and spaced about the grommet axis, to facilitate interfit of individual of the multiple grommet shoulders against the seating surface.
Yet another object is the provision of rod and grommet interengaged surfaces to transmit loading from the grommet to the flange when the rod is tightened. A drum lug to which the tensioner rod is threadably attached may be aligned with the grommet and spaced from it, to contribute with force direction to wedgeably seat the grommet, as referred.
A further object is to provide multiple of such grommets, for interaction with a series of tensioner rods spaced about the drum shell, and acting in concert to block unwanted changes in drum head adjusted tensioning.